1. Field of Invention
The present disclosure relates in general to an apparatus and method for fracturing an oilfield tubular.
2. Description of Prior Art
Drilling a wellbore for production of oil and/or gas typically involves inserting a drilling string having a drill bit on its lower end through a wellhead assembly mounted over hydrocarbon bearing strata. Blowout preventers are often mounted onto the wellhead assembly for shearing the drill string, or other tubular in the wellhead assembly, and sealing in the wellbore. Offshore drilling rigs normally employ a riser to connect the subsea wellhead with the drilling rig; where the blowout preventer is located at a lower end of the riser. Generally, blowout preventers include shear rams for shearing the drill string or tubular and pipe rams sized to close and seal around pipe strings of certain diameters.
Typically pipe shear rams have two rams with a blade mounted on an end of each ram. Hydraulically driven pistons are usually included to move the rams toward each other to shear pipe extending through the blowout preventer. Often, one of the blades is higher than the other and slides over the lower one when the shear rams close. The hardness of the tubular being sheared, in combination with the geometry of how the shear blades contact the tubular, requires that a significant force be applied to the shear blade to successfully shear the tubular.